Professor Snape is one of the Harry Potter franchise’s most complex characters, so it’s no surprise that Alan Rickman found the portrayal difficult at times.

Mementos of Rickman’s are going to be auctioned off by Neil Pearson Rare Books, including personal letters that shed light on some of his frustrations playing Snape. Rickman — who died of cancer in 2016 — appeared in the role in all eight films from 2001 to 2011.

One letter is from producer David Heyman, who sent Rickman a thank-you note after 2002’s Harry Potter and the Chamber of Secrets. “Thank you for making HP2 a success,” it reads. “I know, at times, you are frustrated but please know that you are an integral part of the films. And you are brilliant.”

The Independent obtained a note Rickman penned while working on the sixth film, Harry Potter and the Half-Blood Prince, released in 2009. Titled “Inside Snape’s Head,” it describes the actor’s frustration over how director David Yates approached Snape’s storyline. “It’s as if David Yates has decided that this is not important in the scheme of things i.e. teen audience appeal,” he writes.

Rickman’s scripts for all of the films are included in the auction. Snape’s lines are highlighted and many feature extensive notes in the actor’s handwriting, shedding light on his creative process and sometimes the atmosphere on the set. There is also extensive handwritten correspondence with J.K. Rowling discussing Snape’s character development. A few of their exchanges are teased online.

“Just back from weeks away and had to send a line about what you wrote in the souvenir programme for Hallows II. Made me very tearful. Thank *you* for doing justice to my most complex character,” says one letter from Rowling.

In 2006, she also sent him a Christmas card, writing, “Just completed *the* Snape chapter. It is so very strange, finishing…” Guess you’ll have to pony up some cash to see what the rest of the note says — and it will cost you. The entire collection is valued at £950,000 (over $1,250,000).